Quasiparticle Research Articles

Electric-Field Control of the Local Thermal Conductivity in Charge Transfer Oxides.

Phonons, the collective excitations responsible for heat transport in crystalline insulating solids, lack electric charge or magnetic moment, which complicates their active control via external fields. This presents a significant challenge in designing thermal equivalents of basic electronic circuit elements, such as transistors or diodes. Achieving these goals requires precise and reversible modification of thermal conductivity in materials. In this work, the continuous tuning of local thermal conductivity in charge-transfer SrFeO3-x and La0.6Sr0.4CoO3-x oxides using a voltage-biased Atomic Force Microscopy (AFM)tip at room temperature is demonstrated. This method allows the creation of micron-sized domains with well-defined thermal conductivity, achieving reductions of up to 50%, measured by spatially resolved Frequency Domain Thermoreflectance (FDTR). By optimizing the oxide's chemical composition, the thermal states remain stable under normal atmospheric conditions but can be reverted to their original values through thermal annealing in air. A comparison between Mott-Hubbard and charge-transfer oxides reveals the critical role of redox-active lattice oxygen in ensuring full reversibility of the process. This approach marks a significant step toward fabricating oxide-based tunable microthermal resistances and other elements for thermal circuits.

Propagation gap for shear waves in binary liquids: Analytical and simulation study.

Transverse collective excitations in 50-50 and 80-20 Lennard-Jones binary liquid mixtures are studied for different mass ratio of components R at fixed numerical densities. Increasing the mass ratio results in a growing difference between frequencies of shear waves and transverse optic modes. We report an increase in the propagation gap width for shear waves with mass ratio of components and compare it to the gap width expression, known from the transverse dynamics of simple liquids. A four-variable dynamic model of transverse dynamics in binary liquids with an account of cross correlations between total-mass and mass-concentration transverse current fluctuations is solved analytically in the long-wavelength region. An equation for the propagation gap of shear waves for binary liquids is reported and analyzed.

Building Narratives Through Empathy: The Role of Empathy Mechanisms and Associative Thinking in Creative Writing

ABSTRACTEmpathy emerges as a pivotal skill in creative writing, yet previous studies lack an understanding of empathy's multidimensionality and specific impact of its facets on the capacity to generate narrative stories. This cross‐sectional study delved into the various cognitive and affective empathy facets—that is, perspective‐taking, online simulation, emotion contagion, proximal responsivity, and peripheral responsivity—and their contributions to creative writing. Further, it examined the mediating effects of associative thinking—conceptualized as a common empathy‐creativity resource—on the relationship between empathy facets and creative writing. Two‐hundred twenty participants (university students) completed performance‐based tasks and self‐report measures of creative writing, associative thinking, and empathy. A latent mediation model implemented in Structural Equation Modeling indicated two effects of empathy facets on creative writing, with perspective‐taking emerging as a positive predictor. Additionally, peripheral responsivity (i.e., affect sharing in indirect contexts) exhibited an indirect positive influence on creative writing, mediated by associative thinking. In summary, associative thinking appears to be an important ingredient in both empathy and creative writing, while cognitive empathy, specifically intuitive perspective‐taking, contributes significantly to creative writing skills. Future studies should further explore these connections and their causalities, possibly using experimental or longitudinal approaches.

Quasi-particle Propagation Across Semiconductor–Mott Insulator Interfaces

As a prototypical example for a heterostructure combining a weakly and a strongly interacting quantum many-body system, we study the interface between a semiconductor and a Mott insulator. Via the hierarchy of correlations, we derive and match the propagating or evanescent (quasi) particle solutions on both sides and assume that the interactions among the electrons in the semiconducting regions can be absorbed by an effective potential. While the propagation is described by a band-like dispersion in both the weakly and the strongly interacting case, the inverse decay length across the interface follows a different dependence on the band gap in the Mott insulator and the semiconductor. As one consequence, tunnelling through a Mott insulating layer behaves quite differently from a semiconducting (or band insulating) layer. For example, we find a strong suppression of tunnelling for energies in the middle between the upper and lower Hubbard band of the Mott insulator.

Significant magnon contribution to heat transfer in nickel nanowires

Magnons, quantized spin waves arising from collective excitations of spins, are typically considered negligible contributors to heat transfer. However, recent studies on low-dimensional magnetic materials have challenged this notion, revealing significant magnon-mediated heat transport. The underlying physics behind this phenomenon, however, remains poorly understood. In this study, we observed a significant reduction in heat transfer in nickel nanowires under the influence of a magnetic field. Our theoretical model revealed a substantial magnon contribution of up to 30 % to nanowire heat transfer. The reduction in heat transfer under a magnetic field stemmed from a drastic decrease in the magnon mean free path (MFP). This decrease in MFP was primarily attributed to suppressing long wavelength magnons with a longer MFP. Our findings provide deeper insights into heat transfer mechanisms in nanoscale ferromagnetic materials and offer valuable guidance for the design of future spintronic devices.

Origin of correlated diffuse scattering in the hexagonal manganites

We use a combination of first-principles density-functional calculations and spin-dynamics simulations to explain the unusual diffuse inelastic neutron scattering in the hexagonal multiferroic yttrium manganite, YMnO3. Using symmetry considerations, we construct a model spin Hamiltonian with parameters derived from our density-functional calculations and show that it captures the measured behavior. We then show that the observed directionality in the structured diffuse scattering in momentum space is a hallmark of the triangular geometry, and that its persistence across a wide range of temperatures, both above and below the Néel temperature TN, is a result of the strong magnetic frustration. We predict that this diffuse scattering exists in a yet-to-be-observed modulated continuum of energies, that its associated spin excitations have distinct in-plane and out-of-plane character, and that vestiges of the magnetic frustration persist into the sub−TN state. Finally, we show that visualizing the magnetic order in terms of composite trimer magnetoelectric monopoles and toroidal moments, rather than individual spins, provides insight into the real-space fluctuations, revealing clusters of emerging order in the paramagnetic state, as well as collective short-range excitations in the ordered antiferromagnetic phase. Our understanding of this directional diffuse scattering in such a wide temperature range, both below and above TN, provides new insight into the magnetic phase transitions in classical frustrated systems. Published by the American Physical Society 2024

Trimerization-induced zone-folded phonons in 1T′-TaTe2

The trimerized state is an intriguing structure in the superlattice with three unit cells distorted periodically. Here, we report on two kinds of featured phonon modes induced by the trimerization transition in 1T′-TaTe2. One is the almost temperature-independent zone-folded mode, stemming from the collective excitation due to the superlattice formation and the other is the normal mode with the step-like temperature-dependent intensity and frequency, which is the characteristic of the first-order transition of the trimerization. Furthermore, the trimerization can be totally suppressed when Mo-dopant content is less than 6 at. %. Our work not only unveils the featured phonon modes in trimerized system but also provides a pathway to identify the multimerization transition in solids by Raman spectroscopy.

Global shift symmetry on an ADM hypersurface: Toward emergent gravity

Generalized symmetries and their spontaneous breakdown serve as the fundamental concept to constrain the many-body entanglement structure, which allows us to characterize quantum phases of matter and emergent collective excitations. For example, emergent photons may be understood by spontaneous 1-form symmetry breaking, which results from a long-ranged entanglement structure between UV microscopic degrees of freedom. In this study, we show that emergent “gravity” may also arise in a similar fashion, where quotes have been used to emphasize that the symmetry-constrained gravitons show unconventional properties compared to usual gravitons. As the electric 1-form symmetry in Maxwell theory is realized as a global shift symmetry of the spatial component of the U(1) gauge field, generated by the electric field, we demonstrate that a constant shift of the Arnowitt-Deser-Misner (ADM) metric on the spatial hypersurface can be viewed as a global symmetry, generated by the ADM canonical momentum. Deriving a vector-type conserved charge from the variation of action, we construct a shift symmetry operator. Considering a Wick rotation, we demonstrate that a gravitational Wilson loop is charged under the action of this shift symmetry operator, which thus confirms the existence of a generalized global symmetry on the ADM hypersurface. Based on the Ward identity, we show that the spontaneous breaking of this global shift symmetry may give rise to a nonpropagating massless symmetric gauge field at the boundary of the hypersurface. Published by the American Physical Society 2024

Optical properties of rutile TiO[formula omitted] with Zr, Mo, Zn, Cd impurities

To explore quasiparticle (QP) energy gaps and photoabsorption spectra of rutile TiO2 with nonmagnetic transition metal (Zr, Mo, Zn, Cd) impurities, we conducted a Γ-point only GW ＋ Bethe–Salpeter equation (BSE) calculation on a 72 (or 71) atom supercell. Our findings reveal that Zn and Cd impurities must coexist, at least partly, with oxygen vacancies to maintain charge neutrality. Among the systems considered, Mo, Zn, or Cd doped rutile TiO2 may exhibit optical absorption and catalytic activity under visible light. The resulting QP energy gaps (ΔɛQP) and photoabsorption energies (PAEs) are fairly in good agreement with both experimental and theoretical data currently available. The necessary conditions for the applicability of the Γ-point only approach in the GW ＋ BSE framework were found to be: (1) The Γ-point only GW calculation should reproduce a reasonable band gap. (2) The “superficial” exciton binding energy (the diagonal element of Wvc;vc−2Xvc;vc between v= VBM and c= CBM, where W and X are the direct and exchange terms of the BSE matrix elements, respectively) must be positive or marginally negative. (3) The “real” exciton binding energy (ΔɛQP− the lowest PAE) should be positive, even if it is exceptionally small.

Physical Engagement in Face-to-Face Interaction Is Associated with Depressive Symptoms of Interaction Partners in the Workplace

Individuals develop interdependence through interactions. The process of physical coordination during face-to-face interactions facilitates relationship formation, emotional experiences, and emotional contagion. Workplaces inherently involve organic and continuous face-to-face interactions. Examining the interpersonal association between physical movement and emotional state among employees in the workplace is crucial for understanding an organization’s emotional dynamics. This study investigated the association between patterns of physical engagement during face-to-face interactions and depressive symptoms with those of interaction partners in a real-world workplace setting. The analysis utilized face-to-face interaction data from 449 employees across ten organizations, measured using wearable devices, along with a self-reported depression scale. The results showed that employees’ average physical engagement negatively correlated with the average depressive symptoms of their interaction partners, rather than their own. The association remained robust regardless of the number of relationships or workplace type. Furthermore, the depressive symptoms of individuals who had a significant influence on interpersonal relationships within organizations negatively correlated with their and their partner’s physical engagement. Our findings have important implications for the epidemiological understanding of organizational mental health in relation to face-to-face interactions among employees.

Collective excitations in magnetic topological insulators and axion dark matter search

We investigate collective excitations in magnetic topological insulators (TIs) and their impact on axion detection. In the three-dimensional TI model with the Hubbard term, the effective action of magnons and amplitude modes is formulated by dynamical susceptibility under the antiferromagnetic and ferromagnetic states. One of the amplitude modes is identified as “axionic” quasi-particle and its effective coupling to the electromagnetic fields turns out to be enhanced by about four orders of magnitude larger than the previous estimate, which may drastically change the sensitivity of the axion search using “axion” in magnetic TIs.

Possible relations between emotional contagion and social buffering

Emotional contagion can be defined as the transfer of an emotional state from the demonstrator of that state towards an observer. Social buffering is a process by which the demonstrator has a reduced stress response due to the presence of one or more other individuals. While both processes are well studied separately, it is unknown whether and how both processes are related. Therefore, the aim of this study was to investigate the relation between emotional contagion and social buffering in pigs. Hereto correlations were performed between measures of emotional contagion (i.e., the difference in behaviour of observer pigs between a situation with and without demonstrator pigs present) and measures of social buffering (i.e., the difference in behaviour of demonstrator pigs in a negative situation with and without observer pigs present). The results did not point towards a clear and consistent relation as only few and contrasting correlations between measures of emotional contagion and social buffering were found, and after correcting for chance no significant correlations remained. To conclude, more research is needed on the relation between emotional contagion and social buffering to shed light on how and when emotions will spread through and/or are buffered in a group of animals.

The contribution of vulnerability to emotional contagion to the expression of psychological distress in older adults

This study examines the differential weight of a wide range of factors—sociodemographic factors, indicators of autonomy, social support, coping styles, vulnerability to emotional contagion, and empathy—in the presence of two profiles of psychological distress and in their absence. This cross-sectional study included 170 older adults. As assessed by the Hospital Anxiety and Depression Scale (HADS), 65.9% of the individuals in the sample had a clinical or subthreshold level of anxiety and depression (score > 1). Based on the HADS’s clinical cutoff scores for the anxiety and depression subscales, three profiles were created for the no distress, anxiety, and anxious depression groups. The profiles did not differ on demographic indicators except for sex. Vulnerability to emotional contagion, satisfaction with the social network and coping styles emerged as factors weighing the likelihood of being in either of the psychological distress groups relative to individuals with no distress. After controlling for adversity and psychotropic treatment, vulnerability to emotional contagion had the strongest relationship with both psychological distress profiles. Future research, such as a prospective longitudinal study, may provide an opportunity to explain the direction of the relationship between psychological distress and the factors studied, particularly vulnerability to emotional contagion.

JellyCat: Marketing Strategies Based on Customer Emotions and Sentiment

The exploration of consumer psychology within marketing has long been recognized as a fundamental aspect, with a particular emphasis on consumer emotions and sentiment. This study delves into the case of JellyCat to thoroughly investigate its marketing strategies, which are intricately intertwined with consumer emotions and sentiments. It offers practical insights and recommendations to address current deficiencies. Drawing from the 7P model, this paper integrates theories such as the Emotional Contagion Theory and the Expectancy-Disconfirmation Model to critically analyze JellyCat’s utilization of sentiment-based marketing across various dimensions: product, price, place, promotion, people, physical evidence, and process. Through a comprehensive examination of JellyCat’s approach, this study aims to provide valuable insights and guidance for similar companies, presenting actionable methods and recommendations to rectify any shortcomings in organizational operations. Furthermore, it seeks to identify key successes and valuable lessons learned, aiming to inform and inspire other companies seeking to enhance their marketing strategies in alignment with consumer emotions and sentiments. By leveraging these findings, companies can effectively cultivate stronger connections with their target audience and bolster their marketing efforts in a manner that resonates deeply with consumer emotions and sentiments.

Near-Infrared Light-Driven CO2 Reduction on Cup-Stacked Carbon Nanotubes.

Carbon nanotubes feature one-dimensional nature of collective excitations, wherein strong confinement of surface plasmons severely hinders the liberation of hot electrons (HEs), posing grand challenges for their utilization in photochemistry. In this study, we prototypically achieved directed HEs flow and extraction in hybrid plasmonic CNN based on cup-stacked carbon nanotubes (CSCNTs), taking advantage of their privileged edge-plane sites. The localized pz electronic states and accessible intersubband plasmon excitations in the near-infrared (NIR) regime stands in striking contrast to the conventional concentric carbon nanotubes, as evidenced by combined photo-induced force microscopy (PiFM) and transient photocurrent response. The hybrid comprising intimately integrated CSCNTs-C3N4 effectively sustains interfacial electronic states and underlies the energy extraction out of plasmonic components. The CNN demonstrates almost near-unity NIR light-driven CO2 reduction to CO with a rate of 1.35 µmol g-1 h-1. This work sheds light on the exploitation of metal-free carbon-based plasmonic nanostructures for photocatalytic applications.

Dispersionless Flat Mode and Vibrational Anomaly in Active Brownian Vibrators Induced by Stringlike Dynamical Defects.

In recent years, active Brownian particles have emerged as a prominent model system for comprehending the behaviors of active matter, wherein particles demonstrate self-propelled motion by harnessing energy from the surrounding environment. A fundamental objective of studying active matter is to elucidate the physical mechanisms underlying its collective behaviors. Drawing inspiration from advancements in molecular glasses, our study unveils a low-energy "flat mode" within the transverse spectrum of active Brownian vibrators-a nearly two-dimensional, bidisperse granular assembly. We demonstrate that this collective excitation induces an anomalous excess in the vibrational density of states (VDOS) beyond the phononic Debye contribution. We characterize the properties of this flat mode by exploring the parameter space of our experimental system and tuning the packing fraction, the vibrational frequency, the particle size ratio, and the mixture ratio. Additionally, we establish through empirical evidence that stringlike dynamical defects, discerned via the spatial distribution of each particle's contribution to the reduced transverse VDOS, serve as the microscopic origin of the flat mode and its associated anomalies.

Near‐Infrared Light‐Driven CO2 Reduction on Cup‐Stacked Carbon Nanotubes

Carbon nanotubes feature one‐dimensional nature of collective excitations, wherein strong confinement of surface plasmons severely hinders the liberation of hot electrons (HEs), posing grand challenges for their utilization in photochemistry. In this study, we prototypically achieved directed HEs flow and extraction in hybrid plasmonic CNN based on cup‐stacked carbon nanotubes (CSCNTs), taking advantage of their privileged edge‐plane sites. The localized pz electronic states and accessible intersubband plasmon excitations in the near‐infrared (NIR) regime stands in striking contrast to the conventional concentric carbon nanotubes, as evidenced by combined photo‐induced force microscopy (PiFM) and transient photocurrent response. The hybrid comprising intimately integrated CSCNTs‐C3N4 effectively sustains interfacial electronic states and underlies the energy extraction out of plasmonic components. The CNN demonstrates almost near‐unity NIR light‐driven CO2 reduction to CO with a rate of 1.35 µmol g–1 h–1. This work sheds light on the exploitation of metal‐free carbon‐based plasmonic nanostructures for photocatalytic applications.

Personal Experience Sharing Cat Meme Videos among Contemporary Chinese Young People: Take the Bilibili Platform as an Example

Abstract: This study explores the phenomenon of personal experience-sharing cat meme videos among contemporary Chinese young people on the Bilibili platform. By employing qualitative content and discourse analysis on two popular cat meme videos and their comments, this research delves into how these videos foster empathetic communication, thereby forming an interactive connection between creators and audiences. The research finds that the cat meme video connects the real world with the video world through the means of cat meme symbol, scene construction, narrative method, and atmosphere creation. The cat meme video absorbs the audiences emotional perception and identification, so as to promote the audiences emotional fit with the cat meme video and thus trigger the audiences empathy. The findings indicate that viewers are not merely passive recipients but active participants who, through their interactions, enhance the emotional transmission of the videos. This two-way empathy communication leads to the establishment of a supportive online community, where individuals share similar experiences, offer advice, and provide emotional support. Consequently, cat meme videos on Bilibili serve as a medium for young people to express their social emotions, creating a vibrant and emotionally connected online community.

Emotional contagion to vocal smile revealed by combined pupil reactivity and motor resonance

The interplay between the different components of emotional contagion (i.e. emotional state and facial motor resonance), both during implicit and explicit appraisal of emotion, remains controversial. The aims of this study were (i) to distinguish between these components thanks to vocal smile processing and (ii) to assess how they reflect implicit processes and/or an explicit appraisal loop. Emotional contagion to subtle vocal emotions was studied in 25 adults through motor resonance and Autonomic Nervous System (ANS) reactivity. Facial expressions (fEMG: facial electromyography) and pupil dilation were assessed during the processing and judgement of artificially emotionally modified sentences. fEMG revealed that Zygomaticus major was reactive to the perceived valence of sounds, whereas the activity of Corrugator supercilii reflected explicit judgement. Timing analysis of pupil dilation provided further insight into both the emotional state and the implicit and explicit processing of vocal emotion, showing earlier activity for emotional stimuli than for neutral stimuli, followed by valence-dependent variations and a late judgement-dependent increase in pupil diameter. This innovative combination of different electrophysiological measures shed new light on the debate between central and peripherical views within the framework of emotional contagion.

Strange sounds

This latter addresses the effects of long-ranged and/or retarded interactions on the bosonic collective modes in the so-called ‘strange metals’. Recently, there have been conflicting reports on the very existence of such stable collective excitations and their properties. Extending a number of approaches that have been previously used in the analyses of the standard Fermi liquid one finds evidence for, both, conventional and novel behaviors of the non-Fermi-liquid counterparts of the zero-, shear-, and other ‘sounds’.